Device for synchronizing the slackening of the needle thread with the threadcutting, with timing of the slackening of the needle thread and independent control of the delay of disc opening for lockstitch sewing machines

ABSTRACT

An electropneumatic device is disclosed for synchronizing the thread slackening mechanism of a lock stitch sewing machine with the cutting of the thread, said device being capable of controlling the delay in the opening of the thread tensioning discs independently of the stroke of the piston which actuates the thread cutter. In its simplest embodiment, the device comprises, in addition to a pneumatic thread cutting device and a pneumatic device for controlling the tension of the needle thread and a source of compressed air, two valve means, the first of which is connected to the thread cutting mechanism and to a flow restrictor, the second valve means being connected to the thread tension control mechanism and to a storage reservoir for compressed air.

Ilnited States Patent Conti 1 ,Ian. I, 11974 DEVICE FOR SYNCI-IRONIZINGTHE 3,443,540 5/1969 Hannemann et a1 112/252 SLACKENHNG OF E NEEDLETHREAD 3,528,379 9/1970 Miller 1 12/254 X 3,667,410 6/1972 Bianchill2/219 B WITH THE THREADCIJTTING, WITH TIMING OF THE SLACKENING OF THENEEDLE TIIREAD AND INDEPENDENT CONTROL OF THE DELAY OF DISC OPENING FORLOCKSTITCII SEWING MACHINES [76] Inventor: Cesare L. Conti, Via Varese18,

Milan, Italy [22] Filed: Nov. 20, 1972 [2]] Appl. No.: 308,297

[30] Foreign Application Priority Data Nov. 24, 1971 Italy 31523 A/71[52] 1U.S. C1. 1112/252, 112/254 [51] Int. Cl D05b 65/02 [58] FieldofSearch 112/219 R,219 A,

[56] References Cited UNlTED STATES PATENTS 3,298,341 1/1967 Bonis112/219 B Primary ExaminerWerner H. Schroeder Att0rney--Frank .1. Jordan[57] ABSTRACT An electropneumatic device is disclosed for synchronizingthe thread slackening mechanism of a lock stitch sewing machine with thecutting of the thread, said device being capable of controlling thedelay in the opening of the thread tensioning discs independently of thestroke of the piston which actuates the thread cutter. In its simplestembodiment, the device comprises, in addition to a pneumatic threadcutting device and a pneumatic device for controlling the tension of theneedle thread and a source of compressed air, two valve means, the firstof which is connected to the thread cutting mechanism and to a flowrestrictor, the second valve means being connected to the thread tensioncontrol mechanism and to a storage reservoir for compressed air.

3 Claims, 7 Drawing Figures 1* 10.00.100.03 u I -'I o o" 31."- 0000. alue...

DEVICE FOR SYNCI'IIRONIZING THE SLACKENING OF THE NEEDLE THREAD WITH THETHREADCIJTTING, WITH TIMING OF THE SLACIIENING OE THE NEEDLE THREAD ANDINDEPENDENT CONTROL OF THE DELAY OE DISC OPENING EOE IJOCKSTITCH SEWINGMACHINES BACKGROUND OF THE INVENTION This invention relates to a devicefor synchronizing the slackening of the tension of the needle thread andthe cutting, with timing of the slackening of the thread tension andindependent control of the disc opening, particularly for lockstitchsewing machines.

PRIOR ART In the US. Pat. No. 3,635,180 of Jan. 18, 1972 there had beendisclosed and claimed a device for synchronizing the slackening of thethread tension and cutting with timing of the slackening of the tensionof the thread for lockstitch sewing machines. This device essentiallycomprised a thread cutting device which was pneumatically actuated andhad an air feed, a device for controlling the thread tension, alsopneumatically actuated and having an air feed, a source of compressedair, a magnetically actuated control valve connected to said threadcutting device and also to said tension control device and having afirst position for connecting said source to the intake side of saidthread cutting device and a second position for interconnecting theintake side of said thread cutting device for the intake side of saidthread tension control device, so that a pressure applied to saidcutting device in said first position of said valve is discharged fromsaid thread cutting device for actuating said thread tension controldevice in said second position of said valve.

Although the operation of the device as disclosed in the aforementionedpatent is as reliable as desired and is fully satisfactory, it hasproven desirable, in practice to have at hand a device of the kindreferred to above, in which the control of the delay in the opening ofthe disc might take place in a manner which is independent of the(active) return stroke of the actuation piston of the thread cuttingmechanism.

OBJECTS OF THE INVENTION The principal object of the present inventionis thus to provide a device for synchronizing the slackening of theneedle thread tension and the cutting, which not only is equipped withmeans for timing the slackening of the tension of said thread, but alsowith means which are adapted to cause the control of the delay in theopening of the disc to be carried out independently of the (active)return stroke of the cutting device actuating piston.

Another object of the present invention is to provide a synchronizingdevice of the kind referred to above, which is capable of affording agreater accuracy in the regulation of the delay time, thus providing notonly a pneumatic delay device connected to the thread cutting controlpiston, but also an additional pneumatic delay device connected to theactuating piston of the needle thread cutting mechanism.

SUMMARY OF THE INVENTION In its broader aspect, the present inventionthus relates to a device for synchronizing the slackening of the tensionof the needle thread and the cutting, in a sewing machine, characterizedin that it essentially comprises:

a pneumatic thread cutting mechanism, having a compressed air intake;

a pneumatic control device for the tension of the thread, having an airinput and an air output, the latter being terminated by a flowregulator;

a source of compressed air;

a storage reservoir for compressed air;

a first control valve means, magnetically actuated and connected to saidthread cutting device as well as to a rate of flow regulator;

a second control valve means, magnetically actuated and connected tosaid thread tension control device as well as to said compressed airstorage reservoir;

said first magnetically controlled valve means having a first positionfor connecting said compressed air source to the air input of saidthread cutting device, and a second position for connecting the airinput of said thread cutting device to the rate of flow regulatorbelonging to said first valve means;

said magnetically controlled second valve means having a first positionfor connecting said compressed air source to said compressed air storagereservoir, and a second position for connecting said compressed airstorage reservoir to the air input of said thread tension controldevice, and

means for positioning, alternatingly and simultaneously, said first andsaid second magnetically actuated valve means, into said first or saidsecond positions.

The foregoing and other objects, features and advantages of the presentinvention will be better understood from the ensuing description of afew exemplary embodiments, which do not involve any limitation, andwhich are shown in the accompanying drawings.

DRAWINGS FIG. l is an operative diagram of the simplest embodiment ofthe invention, as shown in the at rest configuration and in thatsubsequent to thread cutting;

FIG. 2 is a diagram, similar to that of FIG. ll, and shows the positionin readiness for the active return stroke intended for cutting thethread;

FIG. 3 is an alternative embodiment of the structure shown in FIG. ll,and in a position which exactly corresponds to that of FIG. I, that is,the at rest position;

FIG. 4 shows the embodiment of FIG. 3 in the position in readiness forthe active return, thread cutting, stroke, a position which is similarto that viewed in FIG. 2.

FIG. 5 shows a further embodiment of the invention, in the at restposition and in the position subsequent to the thread cutting operation.

FIG. 6 shows the embodiment of FIG. 5 in the position in readiness forthe active return, thread cutting stroke, and

FIG. 7 is a diagrammatic overall view which shows in a simplified mannerthe arrangement of the several component parts of the pneumatic system,to show the functional connections in a sewing machine, the latterhaving also been merely diagrammatically shown, along with the electricsynchronizing device for the needle-positioning motor (the latter havingbeen shown as a symbol).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Inasmuch as thegeneral operation of a conventional pneumatic device for actuating thethread cutter and the cutting devices connected therewith is generallyknown, this will no longer particularly be described as such: on theother hand, having reference to the US. Pat. No. 3,635,180 recalledabove, it will be seen in that patent a detailed description of such adevice.

It is important to recall, conversely, prior to passing to a detaileddescription of the several embodiments of the present invention, thatthe basic difference between the present invention and the one disclosedand claimed in the US. Pat. No. 3,635,180 lies in that the abovementioned patent had, as its basic feature, the pneumaticinterconnection between the air input of the thread cutting device andthe air input of the thread control device. In the present invention, onthe contrary, such a constructional and functional mutual dependencycannot be found, inasmuch as the thread cutting device and the tensioncontrol device are never pneumatically interconnected with one another.As a matter of fact, the provision of an air storage reservoir and of anadditional rate of flow regulator has just the object of rendering thetwo devices synchronized with one another, but independent of oneanother from a functional standpoint. The result is that the deviceaccording to the present invention affords a sensitivity and anadjustability range which are incomparably wider than those afforded bythe invention the subject of the above mentioned'US. Patent.

Having now particular reference to FIG. 1, there will be seen the maincomponent parts of the device, namely: a source of compressed air, I, inthe form of a pipe section, a first three-way electromagnetic valve,having two positions, 2, the piping 4 which connects the electromagneticvalve 2 with the cutter control piston 3 (an bee seen, diagrammaticallyshown, at 1 l, with the counterblade 12, also diagrammaticallydepicted), a second electromagnetic valve, 2A, having likewise threeways and two positions, an air storage reservoir, R, a piping 4Aconnecting the reservoir R with the valve 2A, a piping 6 which connectsthe electromagnetic valve 2A with the needle thread tension slackeningcontrol piston 5. There can also be seen, diagrammatically shown, thepiston stem 8 having a point which is adapted to penetrate between thediscs 9 and 10 of the thread presser. The diagram of FIG. 1 also shows,in a diagrammatical fashion, at 13, that the piston 3 has one degree offreedom: it should be enabled to oscillate about an axis perpendicularto the sheet of the drawing to follow the motion of the cutter withoutjamming. It can also be seen that one of the ways of the electromagneticvalve 2 is terminated by a flow regulator (restrictor) 7 which is thepneumatic equivalent of a delay device. Another flow regulator, 7A,terminates a piping, 6A, which discharges the air from the piston 5 forslackening the thread tension. An electric main, T, is also shown, whichis intended synchronously to control the two two-positionelectromagnetic valves 2 and 2A. The electromagnetic valve 2A receivescompressed air from the source 1 through the pipe branch 1A.

By examining now the diagrams of FIG. 1 and FIG. 2 conjointly, it can bereadily seen what follows.

As compressed air enters the electromagnetic valve 2, it reaches thepiston 3 via the piping 4 and shifts the cutter 11 towards the right, asviewed on the drawing. Simultaneously, the electromagnetic valve 2Afeeds compressed air, via the pipes 1A and 4A, to the storage reservoirR to fill it up. Meanwhile, the thread tension slackening piston 5 isdischarging the air that it has received through the pipe 6, into thepipe 6A and therefrom into the atmosphere via the flow regulator 7A.This configuration, which is clearly shown in FIG. 2, is theintermediate position, that is to say the one in which the cutter 1 1has been shifted to the right end of its stroke prior to starting thethread cutting stage.

In orser that the operational cycle may be thoroughly understood, itsuffices to recall the three steps, namely:

1. Starting position of FIG. 1: the cutter is at the extreme left.

2. Intermediate position of FIG. 2: the cutter is at the extreme right,and

3. Position of FIG. 1 again: the cutter is at the extreme left once moreand has reached its starting position again.

Summing up, it has been seen that the position of FIG. 2 can be definedalso as a charge position: as a matter of fact, both the thread cuttingcontrol piston 3 and the storage reservoir R are charged with air. Thus,the two electromagnetic valves are in what has been defined hereinbeforeas the first position.

As the electromagnetic valves 2 and 2A switch to the second position,one obtains the configuration of FIG. 1, that is: The air intakes 1 and1A are closed, the piston 3 (biassed by a spring, which can be seen inthe drawings, in a mabber which is exactly akin to that of the piston 5,also equipped with a recoil spring) discharges air through the pipe 4and the flow regulator 7, and the reservoir R charges the piston bypushing it towards the right and, in the meanwhile, the flow regulator7A, connected with the cylinder which contains the piston 5 through thepiping 6A, tenders an additional regulation possibility for thedischarge.

By observing the FIGS. 1 and 2 conjointly, it can be noticed that, inpractice, the flow regulator (restrictor) 7A, is always in operation: inpractice, it is a two-fold pneumatic delay device since it is activeboth in delaying the charging and the discharging of the cylinder whichhouses the piston 5. This possibility is an important and advantageousfeature of the invention, and it should be observed, at the outset, thata similar possibility exists, only for the discharge of the piston 3 bythe agency of the flow regulator 7A and this independently of thepossibility of regulating both the charging and the discharge of thepiston 5. It can now be understood how the device according to thepresent invention affords an extremely wide regulation range since notonly the charging and discharging speeds of cylinders which house thepistons which control the cutting of the thread and the tension of thethread can be regulated independently, but this can be done, moreover,with an extremely high accuracy so as to fulfil, in practice, even theseverest processing requirements.

To summarize now what has been said in connection with FIGS. 1 and 2,the operation of the device described above takes place as follows:

I. Feeding compressed air to the cutter control piston 3 (FIG. 2) and,simultaneously, charging the storage reservoir R: the cutter 11 isshifted towards the right and is prepared to grasp the thread.

2. The return spring of the piston 5 shifts the piston towards the leftand discharges it: air is discharged through the flow regulation device7A and it is thus possible to adjust the speed at which the discs 9 andIt) are brought close to one another.

3. The thread has been cut (FIG. ll) and the electromagnetic valves 2and 2A have meanwhile been brought to their second position. The pistonof the cylinder, 3, is discharged through the pipe 4, theelectromagnetic valve 2 (which is open), and the flow regulator 7. By sodoing, the cutting speed of the cutter 111 can be adjusted in a mannerwhich is totally independent of the regulation of the opening andclosing of the discs 9 and 110, as outlined above. Meanwhile, also theelectromagnetic valve 2A has been switched to its second position (FIG.It) and the air under pressure held in the reservoir R flows, afterhaving passed through the electromagnetic valve 2A (second position),into the cylinder of the piston 5 pushing the same towards the leftagainst the bias of the specially provided spring (shown, thoughunreferenced, in the drawing) and thus the stem 3 can, with its pointedend, open the discs of the thread tension regulating device: at thisstage it is important to observe that the mode of operation (openingspeed and time) of the discs can be adjusted in an independent mannersince the cylinder which houses the piston 5 is also connected to thepipe 6A, which is terminated by the flow regulating device (restrictor)7A. Thus, by properly calibrating the device 7A any desired mode ofregulation of the opening speed of the discs 3 and 10 can be obtained.In the reverse mode, on account of the characteristic arrangement of thepipes 6 and 6A, of the cylinder of the piston 5 and of the flowregulator 7A, also the closing (approaching) speed of the discs 9 and MDcan be adjusted as desired.

Once again, it should be observed that no direct pneumatic connectionever exists between the piston 3 and the piston S.

The alternative embodiment depicted in FIGS. 3 and 4! is very similar tothe embodiment described immediately above in connection with FIGS. 1and 2, a single detail excepted. The piston 3, in the embodiment ofFIGS. 3 and 4, is no longer spring biassed, but is a double actingpiston. The electromagnetic valve 2 provides a further pathway whichopens into the piping 1B and the latter is situated, on the cylinder ofthe piston 3, in a position which is opposite to the one at which thepipe 4 is installed. Thus, in the intermediate position of FIG. 4 thepressure which charges the cylinder of the piston 3 acts, rather thanagainst a spring bias, against the pressure obtaining in the portion ofthe cylinder which is at the right of the piston 3, so that the aircontained in the right portion of the cylinder of 3, is discharged sincethe electromagnetic valve 2, in its first position, establishes acommunication, inter alia, between the right chamber of the cylinder of3 with the atmosphere (FlG. 4). in the configuration of FIG. 3, on thecontrary, the leftward bias of the spring against the piston 3 isreplaced by the pressure of the air which arrives through theelectromagnetic valve and the pipe TB, into the right chamber of thecylinder of 3. The air contained in the left chamber of the cylinder of3 is discharged in a regulated manner in this meanwhile, through thepiping 4, the electromagnetic valve 2 in its second position, and theflow regulator (restrictor) 7. In the remainder, the operation is theexact counterpart of that of the embodiment of FIGS. l and 2, so that adetailed description of the operation thereof need not be repeated. Itwill be noticed, in this connection, that all the apparatus which reachthe second electromagnetic valve 2A, are perfectly identical to thosewhich have been shown in FIGS. 11 and 2.

As regards now the embodiment shown in FIGS. 5 and 6, it should beobserved that in this Figure all the component parts which have beenshown in FIGS. 3 and 4 can be found, with the addition of a thirdelectromagnetic valve, ZB, having two ways which is synchronized, asusual, with the other two electromagnetic valves 2, and 2A. To theelectromagnetic valve 28 arrive, on the one side, the pipe TB whichconnects the valve to the piston 3, and, on the other side, a pipesection which is inserted between the two branches 1A and 1C connectedto the compressed air source I. The branch 1C, which is an extension ofthe branch 1A, is connected again to the electromagnetic valve 2A, in amanner which is similar to what has been seen for the previouslydescribed embodiments. The operation of the embodiment of FIGS. 5 and 6is very much the same as that of the previously described embodiments:there is only to observe that the discharge of the cylinder of 3 as wellas its charging, as regards the chamber placed at the right of thepiston 3, as viewed in the drawings, are entrusted to a speciallyprovided member, that is, the supplementary electromagnetic valve 2B asindicated above.

Summing up as regards the embodiment of FIGS. 5 and 6, the operationalstages are the following:

1. Charging the cylinder of 3 through 1-2-4 and discharging the rightportion of 3 through 113 and the electromagnetic valve 2B: theelectromagnetic valve does not receive air from 1A. Simultaneously, R ischarged through RA and 1C and the electromagnetic valve 2A, while 5 isbeing discharged through 6A and 7A, (FIG. 6).

2. Discharging 3 through 4, electromagnetic valve 2 and restrictor 7while the right portion of 3 is charged through lA-2B-llB, theelectromagnetic valve 2A being closed towards the branch 1C of the airfeed. At the same time, R, through 4A, the electromagnetic valve 2A and6, charges the piston 5 and causes the discs to be spread out. Theopening speed and time for the discs are determined by the calibrationof the restrictor 7A, as has already been shown, and by the volurne ofthe reservoir R.

3. The same sequence as for ll) so that the operational cycle is closedand is repeated indefinitely.

In the drawings, as is customary, the closely scattered dots representhigh pressure (that is, air feed) and the thinly scattered dotsrepresent low pressure, that is, discharge of air, either directly orthrough the restrictor.

FIG. 7 gives a summary showing of the embodiments which have beendescribed above: in this Figure there have been indicated in anextremely diagrammatical manner the functional connections and thepositions of the several component parts as indicated in the otherFigures: S symbolically connotes the electric synchronizing device forthe positioning of the needle, whereas the other numerals remind theparts described in the Figures from I to 6, to show, in a simplified butsufficiently clear way, how the several operative members are connectedwith each other.

What is claimed is:

l. A device for synchronizing the slackening of the tension of theneedle thread and the cutting, with timing of the slackening of thethread tension and independent control of the delay of the opening ofthe disc, for

lockstitch sewing machines, characterized in that it essentiallycomprises:

a pneumatic device for cutting the thread, having an input forcompressed air;

a pneumatic device for controlling the thread tension, having an inputfor the air and an air output terminated by a flow regulator;

a source of compressed air;

a storage reservoir for compressed air;

a first control valve means, magnetically actuated and connected to saidthread cutting device as well as to a flow regulator;

a second control valve means, magnetically actuated and connected tosaid thread tension control device as well as to said compressed airstorage reservoir;

said first magnetically actuated valve means having a first position forconnecting said compressed air source to the air input of said threadcutting device, and a second position for connecting the air input ofsaid thread cutting device to the flow regulator belonging to said firstvalve means;

said second magnetically actuated valve means having a first positionfor connecting said compressed air source to said compressed air storagereservoir, and a second position for connecting said compressed airstorage reservoir to the air input of said thread tension controldevice, and

means for positioning, alternatingly and simultaneously, said first andsaid second magnetically actuated valve means into said first or saidsecond positions.

2. A device according to claim 1, characterized in that said threadcutting control pneumatic device further comprises a second input forcompressed air connected by a pipe to a further way of said first valvemeans.

3. A device according to claim 1, characterized in that it comprises anadditional valve means, synchronized with said first and second valvemeans, for controlling the feed and the discharge of the compressed aircoming from said source to said second input for compressed air of saidpneumatic thread cutting device, a piping being provided for connectingsaid second input to said additional valve means.

1. A device for synchronizing the slackening of the tension of theneedle thread and the cutting, with timing of the slackening of thethread tension and independent control of the delay of the opening ofthe disc, for lockstitch sewing machines, characterized in that itessentially comprises: a pneumatic device for cutting the thread, havingan input for compressed air; a pneumatic device for controlling thethread tension, having an input for the air and an air output terminatedby a flow regulator; a source of compressed air; a storage reservoir forcompressed air; a first control valve means, magnetically actuated andconnected to said thread cutting device as well as to a flow regulator;a second control valve means, magnetically actuated and connected tosaid thread tension control device as well as to said compressed airstorage reservoir; said first magnetically actuated valve means having afirst position for connecting said compressed air source to the airinput of said thread cutting device, and a second position forconnecting the air input of said thread cutting device to the flowregulator belonging to said first valve means; said second magneticallyactuated valve means having a first position for connecting saidcompressed air source to said compressed air storage reservoir, and asecond position for connecting said compressed air storage reservoir tothe air input of said thread tension control device, and means forpositioning, alternatingly and simultaneously, said first and saidsecond magnetically actuated valve means into said first or said secondpositions.
 2. A device according to claim 1, characterized in that saidthread cutting control pneumatic device further comprises a second inputfor compressed air connected by a pipe to a further way of said firstvalve means.
 3. A device according to claim 1, characterized in that itcomprises an additional valve means, synchronized with said first andsecond valve means, for controlling the feed and the discharge of thecompressed air coming from said source to said second input forcompressed air of said pneumatic thread cutting device, a piping beingprovided for connecting said second input to said additional valvemeans.